The present invention relates to a transport cylinder gripper pad height adjustment device which adjusts the height of a gripper pad of a transport cylinder in, e.g., a sheet-fed offset rotary printing press in accordance with the thickness of a sheet.
In a sheet-fed offset rotary printing press, a sheet fed by a feeder is gripped by a gripper device equipped in a notch formed in the outer peripheral portion of a transport cylinder including, e.g., an impression cylinder, transfer cylinder, and delivery cylinder, is printed during transportation, and is delivered by a delivery device. The gripper device includes a plurality of pairs of a gripper and a gripper pad which are opposed to each other in the notch. The spaces between all grippers and all gripper pads are opened/closed at once at the sheet gripping positions, and the sheet is transported while being gripped between the grippers and the gripper pads. In a gripper device of this type, the interval between grippers and gripper pads, i.e., the height of the gripper pads needs to be adjusted in accordance with the thickness of a sheet.
A conventional transport cylinder gripper pad height adjustment device includes a notch, gripper pads, gripper pad bar, adjusting bar, biasing means, and operating shaft (see patent reference 1: Japanese Patent Laid-Open No. 11-48449). The notch extends in the cylinder axial direction in the outer peripheral portion of a transport cylinder. The gripper pads are equipped in the notch, and grip a sheet together with grippers. The gripper pad bar has the gripper pads fixed on it, and has a bottom portion inclined with respect to the cylinder axial direction so that it is restricted in movement in the cylinder axial direction and supported to be movable in the cylinder radial direction. The adjusting bar has an inclined surface in contact with the inclined surface of the gripper pad bar, and is supported to be movable in the cylinder axial direction in the notch. The biasing means biases the inclined surface of the gripper pad bar against that of the adjusting bar in the direction to bring them into press contact with each other. The operating shaft moves the adjusting bar in the cylinder axial direction.
The above-mentioned conventional gripper pad height adjustment device has a structure in which the operating shaft extends through a through hole which is formed in the end shaft of the transport cylinder to be directed in the radial direction of the cylinder, so the operating shaft rotates by interlocking with rotation of the transport cylinder. Therefore, the height of the gripper pads cannot be adjusted while the transport cylinder rotates during, e.g., roller cleaning or plate replacement even during non-printing. Thus, it takes a long time for a sheet-fed offset rotary press to prepare for printing.